[Dnsmasq-discuss] Make RA_INTERVAL configureable? Deprecate old prefixes?

Uwe Schindler uwe at thetaphi.de
Thu Jul 25 11:59:59 BST 2013


Hi again,

In addition, I found a relic from the time when the RA_INTERVAL value was hardcoded into radv.c. There is still one:

Line 294: 
	  put_opt6_long(1800); /* lifetime - twice RA retransmit */

Should be:
	  put_opt6_long(RA_INTERVAL * 2); /* lifetime - twice RA retransmit */

I am currently looking into the code to find an easy way how to make the RA_INTERVAL configureable, maybe I can provide a patch. But if it's easy for you, it would be really nice to have this in future versions. So the deprecation of addresses no longer used on the network interface is not my primary concern, more I would prefer to work around the bugs in certain android phones not receiving ICMPv6 messages in standby mode, so the RA_INTERVAL should be configureable (I want to set it to much lower values than 600s, I have a patched version with 6s retransmit running on my debian testing box).

Uwe

-----
Uwe Schindler
H.-H.-Meier-Allee 63, D-28213 Bremen
http://www.thetaphi.de
eMail: uwe at thetaphi.de


> -----Original Message-----
> From: dnsmasq-discuss-bounces at lists.thekelleys.org.uk [mailto:dnsmasq- 
> discuss-bounces at lists.thekelleys.org.uk] On Behalf Of Uwe Schindler
> Sent: Wednesday, July 24, 2013 8:17 PM
> To: dnsmasq-discuss at lists.thekelleys.org.uk
> Subject: Re: [Dnsmasq-discuss] Make RA_INTERVAL configureable?
> Deprecate old prefixes?
> 
> Hi,
> 
> > RA's are not the same as DHCP, there's no such thing as a "lease time".
> > What there is, is preferred and valid lifetimes. What should happen 
> > is that when old address is about to go away, the address for that 
> > prefix on the network adaptor should have its preferred lifetime set 
> > to zero, and dnsmasq will then notice that and send RA's with the 
> > preferred lifetime also set to zero.
> 
> I meant the life time, it was just a typo somehow :-) The idea here 
> was to send preferred_lifetime=0 in RAs for prefixes that disappeared 
> from the interface to "inform" the clients that they are no longer 
> useable (my provider does not route old prefixes after a reconnect 
> with PPP). Currently you have to set the lifetime very low (which 
> produces more traffic on the wire) or manually delete or switch on/off 
> the network adaptors once the router reconnects or the prefix changes for some reason.
> 
> My proposal is to keep a list of "previous prefixes" from the 
> constructor:ethX code and also send those prefixes, but with 
> lifetime=0 to inform all client to no longer use that address. Those 
> 0-lifetime RAs should be sent at least for the length of the original 
> lifetime. Radvd has code to handle this (although it’s a bit buggy).
> 
> Uwe
> 
> 
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